Ideal Weight Calculator

How Much Should I Weigh?

There is no single correct weight for everyone. A healthy weight is better thought of as a range that depends on height, sex, age, the amount of muscle you carry and where your body stores fat. Ideal body weight (IBW) formulas were not created to tell people what they should look like; they were developed in clinical settings to give doctors and pharmacists a consistent reference weight for dosing certain medicines and for estimating nutritional needs. Over time they have also become a popular way for people to get a rough target.

Height is the main input. Taller people have longer bones, larger organs and more muscle, so their healthy weight is higher. Every formula on this page adds a fixed number of kilograms for each inch above five feet, which is why the results climb steadily with height.

Sex matters because men and women differ in body composition. At the same height, men usually carry more muscle and bone and less essential fat, so the male formulas start from a higher base and generally add more per inch. Women naturally need a higher percentage of body fat for hormonal and reproductive health, which is one reason a lean woman and a lean man of the same height can weigh quite different amounts.

Age has a smaller effect in adulthood. Most girls reach their adult height by about 15 and most boys by about 17 or 18, and the formulas assume growth has finished. Later in life, people tend to lose muscle and bone and gain fat even if the scale does not move, so weight alone becomes a weaker guide to health in older adults. For children and teenagers, weight is assessed with sex-specific growth charts rather than IBW formulas.

Body frame matters too. People with a large bone structure can healthily weigh more than those with a small frame. A simple check is wrist size: if your thumb and middle finger overlap easily when wrapped around the opposite wrist, you probably have a small frame; if they just touch, a medium frame; and if they do not meet, a large frame. A common clinical adjustment is to subtract about 10% from the Hamwi result for a small frame and add about 10% for a large one.

Muscle is denser than fat, so two people with the same height and weight can look and function very differently. Athletes often weigh more than any IBW formula suggests while having low body fat and excellent health markers. That is why this calculator also shows the weight range that corresponds to a body mass index (BMI) of 18.5 to 25, the range health agencies use as a screening guide. For 5 feet 10 inches, that range is about 129 to 174 pounds, much wider than the spread of the four formulas.

If your weight falls outside these numbers, it is not a diagnosis. Waist size, blood pressure, blood sugar, cholesterol, fitness and how you feel all add information that a single target weight cannot. A doctor or registered dietitian can help you decide whether a change in weight would benefit your health and how to approach it safely.

Formulas for Finding the Ideal Weight

All four formulas share the same structure: a starting weight for a person exactly 5 feet (152.4 cm) tall plus a fixed increment for every additional inch. They were published by different researchers using different data, which is why they disagree by several pounds at the same height. None is clearly better than the others; together they give a sense of the range.

The Devine formula (1974) was proposed by B. J. Devine to estimate doses of the antibiotic gentamicin and spread quickly into general clinical use. It remains the most widely used IBW equation in medicine, including for drug dosing and for setting ventilator volumes, even though it was not derived from a population study.

The Robinson formula (1983) was a revision based on measured data, intended to correct what the authors saw as overestimates from Devine, especially for women. The Miller formula, published the same year, starts higher at 5 feet but rises more slowly with height, so it gives larger values for short people and smaller values for tall people than the others.

The Hamwi formula (1964) came from G. J. Hamwi's work on diabetes and is still common in nutrition counseling. It was designed to be easy to remember in pounds: 106 pounds for the first 5 feet plus 6 pounds per inch for men, and 100 pounds plus 5 pounds per inch for women, with optional 10% adjustments for frame size.

As a worked example, a man who is 5 feet 10 inches tall is 10 inches over 5 feet. Robinson gives 52 + 1.9 × 10 = 71 kg (156.5 lb), Miller gives 56.2 + 1.41 × 10 = 70.3 kg (155.0 lb), Devine gives 50 + 2.3 × 10 = 73 kg (160.9 lb) and Hamwi gives 48 + 2.7 × 10 = 75 kg (165.3 lb).

IBW = base weight + increment × (height in inches − 60)

Each formula starts from a base weight at 5 feet (60 inches) and adds a fixed amount for every inch above that. The healthy BMI range is 18.5 × height (m)² to 25 × height (m)².

Limitations of our IBW calculator

The formulas use only height and sex. They ignore muscle mass, frame size, age-related changes, ethnicity and fat distribution, so they cannot say whether a particular person is at a healthy weight. They were designed for adults between roughly 5 and 7 feet tall and become less reliable outside that range; below 5 feet the per-inch increments are simply run in reverse. They also do not apply to children, pregnant women or people with conditions that change body composition, such as amputations or severe illness. Treat the results as a starting point for a conversation with a health professional, not as a goal you must reach.

Frequently asked questions

Sources

• CDC – Healthy Weight and Growth
• NIH NHLBI – Aim for a Healthy Weight
• WHO – Body mass index